1. Field of the Invention
A refrigerant purge system to remove noncondensables from a refrigerant circulating through an air conditioning system.
2. Description of the Prior Art
In the air conditioning systems, a refrigerant is alternately expanded into a gaseous state and condensed into a liquid state; heat is absorbed and released, respectively, as a result of such expansion and contraction. When the refrigerant is pure and unadulterated by contaminates such as air and moisture, condensation is complete and the system operates at maximum efficiency; contaminants enter the refrigerant, however, the condensation equipment is unable to condense all such contaminants and the efficiency of the system drops accordingly. In the industry contaminants that cannot be condensed are known as "noncondensables."
Noncondensables enter most air conditioning systems these systems operate under vacuum. Thus those of ordinary skill in the art have attempted to build leak-proof systems, but a truly leak-proof system would be cost prohibitive. Most inventors, however, have accepted the fact of leakage and have developed systems designed to purge noncondensables from the system.
U.S. Pat. No. 5,031,410 shows a refrigeration system thermal purge apparatus that adds a discrete purge refrigerant circuit to the conventional condenser which is exposed to still lower temperatures of an auxiliary condenser.
When the temperature within the auxiliary condenser drops to 18 degrees F., as detected by a thermostat, the contents of said auxiliary condenser are purged to the atmosphere. Although, at 18 degrees F., some separation of condensables and noncondensables will have been achieved, complete separation will not have been achieved; thus, some condensables such as CFC's and HCFC's will be purged into the atmosphere.
U.S. Pat. No. 4,169,356 describes a secondary refrigeration system used to chill the thermal purge apparatus that also utilizes a discrete purge refrigerant circuit to the conventional condenser which is exposed to the still lower temperatures of an auxiliary condenser, but does so without increasing the pressure in the purge vessel and relying solely on thermal migration or pressure differential to motivate the noncondensables into the purge vessel.
U.S. Pat. No. 5,592,826 relates to an air conditioning system comprising a self-regulating flow controller having no moving parts that provides a liquid seal between a purge vessel and the evaporator barrel of a chiller. Circulating refrigerant fluid from a primary air conditioner is preheated in a preheater by hot refrigerant from the chiller prior to its entry into the purge vessel, and the preheater provides a thermal load that enables operation of the purge vessel. The purge unit discharges into a regeneration cell that removes even more refrigerant from the vapors before they are vented to atmosphere. When the regeneration cell requires recharging, it is heated to a predetermined temperature and pressure to release absorbed refrigerant from its absorption media, and the released refrigerant is routed back to the purge vessel and hence through the regeneration cell again prior to discharge of substantially refrigerant-free contaminants into the atmosphere.
U.S. Pat. No. 5,309,729 discloses a thermal purge system includes a purge vessel into which is introduced hot gaseous refrigerant fluid from the outlet of a conventional chiller. A first coil having very cold refrigerant fluid flowing through it is positioned within the vessel so that much of the hot gaseous refrigerant fluid from the chiller is condensed upon contact with the coil. The condensate collects on the bottom of the vessel until it reaches a depth sufficient to initiate a siphoning action by an artesian well, which returns the condensate to the chiller. Uncondensed gases are reheated and re-expanded external to the vessel and returned to the vessel through a second coil in heat transfer relation to the first coil so that further condensation occurs. Noncondensables which remain after the reheating, reexpansion, and recooling are purged to the atmosphere.
None of the prior arts utilize a microprocessor of the purge unit to maximize separation and provide a high level of separation and efficiency nor do the prior arts utilize an external pressure and temperature device along with microprocessor to determine when the purge should run for maximum energy saving and increase operating efficiency and longevity.
Thus, there is a need to provide a purge apparatus that provides a complete separation of condensables and noncondensables before the noncondensables are purged to the atmosphere and to do this via its own on-board, oil-less compressor and via a suitable micro controller.
Moreover, the thermal purge units heretofore known are inefficient to the extent that they do not hold the condensable/noncondensables mixture at a constant low temperature for extended periods of time nor do they raise the pressure high enough in the purge vessel to properly separate out the noncondensables. Thus, insufficient time is available for the condensable and noncondensables to separate. The known systems also do not operate well under high load conditions, i.e., they are inefficient at high temperature gradients because they lack properly sized cooling means and regulate the secondary coiling system with a fixed non variable constant pressure regulator that does not adjust for varying loading conditions. Units currently on the market today rely on thermal migration or a small differential pressure to receive the noncondensables from the system for these reasons.
There is a need, therefore, for a system that does more than merely provide an auxiliary condensation system that does not produce a complete separation of condensables and noncondensables.
When the prior art was considered as a whole, at the time the present invention was made, it neither taught nor suggested to those of ordinary skill in this field how an improved system could be built.